Esophageal squamous cell carcinoma with pagetoid spread: a clinicopathologic study.

Pagetoid spread in esophageal squamous epithelium associated with underlying esophageal adenocarcinoma (EAC) has been well studied. Case reports describing pagetoid spread of esophageal squamous cell carcinomas (ESCC) also exist in the literature. The latter, however, has not been systematically studied. In this study, we report seven cases of pagetoid spread associated with ESCC. The clinical, morphologic, and immunophenotypic profiles of pagetoid spread in the context of ESCC and EAC are compared. Cases of pagetoid spread of ESCC were identified through computerized search of pathology archives at five institutions. Additional cases were identified through manual review of surgical resection cases of treatment naive ESCC in Mass General Brigham (MGB) pathology archive. Clinical history was collected via chart review. Immunohistochemistry for CK7, CK20, CDX2, p53, p63, and p40 was performed on selected cases. A computerized search of pathology archives of five institutions revealed only two cases. A manual review of 76 resected untreated ESCC revealed five additional cases with unequivocal pagetoid spread of ESCC, indicating the condition was not uncommon but rarely reported. Patient age ranged from 54 to 78 years (median, 65). There were six women and one man. One case had in situ disease, five had pT1 (1 pT1a and 4 pT1b), and one had pT3 disease. One of the patients with pT1 tumor had a positive lymph node, while the remaining six patients were all N0. Four tumors were in the proximal to mid esophagus, and three in the distal esophagus. Patient survival ranged from 25 months to more than 288 months. The pagetoid tumor cells demonstrated enlarged, hyperchromatic nuclei with variable amounts of eosinophilic cytoplasm. The cytoplasm was often condensed to the perinuclear area, creating peripheral clearing. By immunohistochemistry, the pagetoid cells were positive for p40 (6/6) and p63 (7/7) and negative for CDX2 (7/7). The tumor cells showed mutant-type staining for p53 in five of seven cases. One of the patients had pagetoid tumor cells at the resection margin and subsequently had recurrent disease 2 years later. All other patients had negative resection margins and did not have local recurrence. Four cases of pagetoid spread in the context of EAC were used as a comparison group. Previously published studies were also analyzed. These tumors were all located in the distal esophagus or gastroesophageal junction. All cases were associated with underlying invasive EAC. Pagetoid spread associated with EAC often had cytoplasmic vacuoles or mucin. They were more frequently positive for CK7 than pagetoid ESCC (p = 0.01). Both ESCC and EAC may give rise to pagetoid spread of tumor cells within surface squamous epithelium. Pagetoid spread from ESCC and EAC have overlapping morphologic features. P40 and p63 immunostains can facilitate the distinction between ESCC and EAC. P53 immunostain can aid in confirmation of malignancy. Understanding their overlapping pathologic features will help pathologists avoid pitfalls and diagnose these lesions correctly on biopsy specimens.

Clinical presentation and outcomes of Helicobacter heilmannii gastritis in children in the New England region of the United States.

OBJECTIVE: To describe the clinical, endoscopic, histologic, and treatment outcomes of Helicobacter heilmannii (H. heilmannii) associated gastritis in children in the New England region of the United States. METHODS: Retrospective study of children (1-18 years) with H. heilmannii identified on gastric mucosal biopsies from two pediatric centers over a 21-year period, January 2000-December 2021. Cases were identified by querying pathology databases at each institution. Demographic and clinical data were obtained from the medical record. Endoscopic and histologic findings were extracted from endoscopy and pathology reports, respectively. RESULTS: Thirty-eight children were diagnosed with H. heilmannii-associated gastritis during the study period. The mean age at diagnosis was 10.1 ± 5.3 years, and 25/38 (66%) cases were male. Abdominal pain (32%) and nausea with or without vomiting (26%) were the most common symptoms. Thirty-two children (84%) had endoscopic findings including gastric nodularity (55%) and erythema (26%). All children had histologic signs of chronic gastritis, including those with normal endoscopic exams. Antibiotic regimens used for treating Helicobacter pylori were frequently prescribed. Of the 17 children who underwent a follow-up endoscopy (range 2-68 months), 15 (88%) did not have H. heilmannii identified on gastric biopsies. CONCLUSION: H. heilmannii was an infrequent but potential cause of epigastric abdominal pain and nausea in our cohort of New England children. While morphologically distinct from H. pylori, the bacteria can result in similar endoscopic and histologic findings of nodularity and chronic gastritis, respectively. The rate of eradication, as assessed by histology following treatment with H. pylori therapies, was below the 90% recommended goal for antimicrobial therapies.

Ang1 and Ang4 differentially affect colitis and carcinogenesis in an AOM-DSS mouse model.

INTRODUCTION: Angiogenin-1 (Ang1) and angiogenin-4 (Ang4) are 14-kDa ribonucleases with potent angiogenic and antimicrobial properties. The role of Ang1 and Ang4 in chronic colitis and colitis-associated cancer has not been previously studied. METHODS: Wild-type (WT) and angiogenin-1 knock-out (Ang1-KO) C57BL/6 mice were given azoxymethane, a colon carcinogen, 2 days in advance of three cycles of 3.5% dextran sodium sulfate (DSS). Disease activity index (DAI) was recorded, a colonoscopy was performed after each DSS treatment, and mice were euthanized (colitis, recovery, cancer) with tissue evaluated by histopathology. Ang1, Ang4, TNF-α, Il-1F062, IL-6, IL-10, IL-23, IL-33 mRNA levels were analyzed by RT-PCR. RESULTS: Ang1-KO mice exhibited more severe colitis compared to WT mice during both the acute (P<0.05) and recovery (P<0.05) phases of each DSS cycle. Consistent with these results, colonic TNF-α, IL1-ß, IL-6, IL-10, and IL-33 mRNA levels were significantly upregulated in Ang1-KO mice (P<0.05). While Ang4 increased to similar levels in both WT and Ang1-KO mice during colitis and recovery phases, WT mice were distinguished by a significant upregulation of Ang1. Interestingly, despite the reduced colitis, WT mice developed significantly more tumors compared to Ang1-KO mice (P<0.05). 134 tumors formed in WT mice (4.6 tumors/mouse) while only 46 tumors formed (1.5 tumors/mice) in Ang1-KO mice, which were also characterized by a 34-fold decrease in Ang4 compared to WT mice and the complete absence of Ang1. CONCLUSIONS: In a mouse model of colitis-associated cancer, Ang1-KO mice develop more severe colitis, but fewer tumors compared to WT mice. Ang1 levels correlate with the severity of colitis and the development of colitis-associated cancer, while Ang4 was upregulated during both colitis and cancer. Ang1 and Ang4 play important regulatory roles in the response to chronic colitis and the development of colitis-associated cancer and may serve as novel therapeutic targets.

Development and evaluation of INT2GRATE: a platform for comprehensive assessment of the role of germline variants informed by tumor signature profile in Lynch syndrome.

The presence of variants of uncertain significance (VUS) in DNA mismatch repair (MMR) genes leads to uncertainty in the clinical management of patients being evaluated for Lynch syndrome (LS). Currently, there is no platform to systematically use tumor-derived evidence alongside germline data for the assessment of VUS in relation to LS. We developed INT2GRATE (INTegrated INTerpretation of GeRmline And Tumor gEnomes) to leverage information from the tumor genome to inform the potential role of constitutional VUS in MMR genes. INT2GRATE platform has two components: a comprehensive evidence-based decision tree that integrates well-established clinico-genomic data from both the tumor and constitutional genomes to help inform the potential relevance of germline VUS in LS; and a web-based user interface (UI). With the INT2GRATE decision tree operating in the backend, INT2GRATE UI enables the front-end collection of comprehensive clinical genetics and tumor-derived evidence for each VUS to facilitate INT2GRATE assessment and data sharing in the publicly accessible ClinVar database. The performance of the INT2GRATE decision tree was assessed by qualitative retrospective analysis of genomic data from 5057 cancer patients with MMR alterations which included 52 positive control cases. Of 52 positive control cases with LS and pathogenic MMR alterations, 23 had all the testing parameters for the evaluation by INT2GRATE. All these variants were correctly categorized as INT2GRATE POSITIVE. The stringent INT2GRATE decision tree flagged 29 of positive cases by identifying the absence or unusual presentation of specific evidence, highlighting the conservative INT2GRATE logic in favor of a higher degree of confidence in the results. The remaining 99% of cases were correctly categorized as INCONCLUSIVE due to the absence of LS criteria and ≥1 tumor parameters. INT2GRATE is an effective platform for clinical and genetics professionals to collect and assess clinical genetics and complimentary tumor-derived information for each germline VUS in suspected LS patients. Furthermore, INT2GRATE enables the collation of integrated tumor-derived evidence relevant to germline VUS in LS, and sharing them with a large community, a practice that is needed in precision oncology.

Abnormal TP53 Predicts Risk of Progression in Patients With Barrett's Esophagus Regardless of a Diagnosis of Dysplasia.

BACKGROUND AND AIMS: Barrett's esophagus (BE) is the precursor to esophageal adenocarcinoma. A major challenge is identifying the small group with BE who will progress to advanced disease from the many who will not. Assessment of p53 status has promise as a predictive biomarker, but analytic limitations and lack of validation have precluded its use. The aim of this study was to develop a robust criteria for grading abnormal immunohistochemical (IHC) expression of p53 and to test its utility as a biomarker for progression in BE. METHODS: Criteria for abnormal IHC of p53 were developed in BE biopsies and validated with sequencing to assess TP53 mutations. The utility of p53 IHC as a biomarker for progression of BE was tested retrospectively in 561 patients with BE with or without known progression. The findings were prospectively validated in a clinical practice setting in 1487 patients with BE. RESULTS: Abnormal p53 IHC highly correlated with TP53 mutation status (90.6% agreement) and was strongly associated with neoplastic progression in the retrospective cohorts, regardless of histologic diagnosis (P < .001). In the retrospective cohort, abnormal p53 was associated with a hazard ratio of 5.03 (95% confidence interval, 3.88-6.5) and a hazard ratio of 5.27 (95% confidence interval, 3.93-7.07) for patients with exclusively nondysplastic disease before progression. In the prospective validation cohort, p53 IHC predicted progression among nondysplastic BE, indefinite for dysplasia, and low-grade dysplasia (P < .001). CONCLUSIONS: p53 IHC identifies patients with BE at higher risk of progression, including in patients without evidence of dysplasia. p53 IHC is inexpensive, easily integrated into routine practice, and should be considered in biopsies from all BE patients without high-grade dysplasia or cancer.

Florid Foreign Body-type Giant Cell Response to Keratin Is Associated With Improved Overall Survival in Patients Receiving Preoperative Therapy for Esophageal Squamous Cell Carcinoma.

While most resection specimens from patients with neoadjuvantly treated esophageal squamous cell carcinoma show therapy-related changes in the form of inflammation and fibrosis, others harbor a florid foreign body-type giant cell response to keratin debris. The purpose of our study was to perform a detailed clinicopathologic analysis of these histologic types of treatment responses and correlate these findings with patient outcome. Clinical and pathologic parameters from 110 esophagogastrectomies were recorded and analyzed. Two main types of histologic responses were observed: inflammatory-predominant response (59%) and florid foreign body-type giant cell response to keratin (41%). Irrespective of cG, cTNM, and amount of residual cancer, florid foreign body-type giant cell reaction was predominantly noted deep within the esophageal wall, while the inflammatory response was restricted to the mucosa, submucosa, and inner half of muscularis propria. Patients with foreign body-type giant cell response showed significantly better overall survival compared with the inflammatory response group (log-rank test P=0.015). Florid foreign body-type giant cell response was the only factor associated with improved survival in a multivariable analysis for overall survival (hazard ratio=0.5; 95% confidence interval=0.3-1.0; P=0.038), but not in the model for disease-specific survival, whereas ypTNM stage II was the only significant risk factor for disease-specific survival in multivariable analysis (hazard ratio=3.4; 95% confidence interval=1.0-11.2; P=0.047). Our results suggest that in addition to the College of American Pathologists Tumor Regression Score and ypTNM stage, subtype of histologic response to therapy may represent another prognostic marker for neoadjuvantly treated esophageal squamous cell carcinoma.

Detection of Mutations in Barrett's Esophagus Before Progression to High-Grade Dysplasia or Adenocarcinoma.

BACKGROUND & AIMS: Barrett's esophagus (BE) is the greatest risk factor for esophageal adenocarcinoma (EAC), but only a small proportion of patients with BE develop cancer. Biomarkers might be able to identify patients at highest risk of progression. We investigated genomic differences in surveillance biopsies collected from patients whose BE subsequently progressed compared to patients whose disease did not progress. METHODS: We performed a retrospective case-control study of 24 patients with BE that progressed to high-grade dysplasia (HGD, n = 14) or EAC (n = 10). The control group (n = 73, called non-progressors) comprised patients with BE and at least 5 years of total endoscopic biopsy surveillance without progression to HGD or EAC. From each patient, we selected a single tissue sample obtained more than 1 year before progression (cases) or more than 2 years before the end of follow-up (controls). Pathogenic mutations, gene copy numbers, and ploidy were compared between samples from progressors and non-progressors. RESULTS: TP53 mutations were detected in 46% of samples from progressors and 5% of non-progressors. In this case-control sample set, TP53 mutations in BE tissues increased the adjusted risk of progression 13.8-fold (95% confidence interval, 3.2-61.0) (P < .001). We did not observe significant differences in ploidy or copy-number profile between groups. We identified 147 pathogenic mutations in 57 distinct genes-the average number of pathogenic mutations was higher in samples from progressors (n = 2.5) than non-progressors (n = 1.2) (P < .001). TP53 and other somatic mutations were recurrently detected in samples with limited copy-number changes (aneuploidy). CONCLUSIONS: In genomic analyses of BE tissues from patients with or without later progression to HGD or EAC, we found significantly higher numbers of TP53 mutations in BE from patients with subsequent progression. These mutations were frequently detected before the onset of dysplasia or substantial changes in copy number.

A Study of Thymidylate Synthase Expression as a Biomarker for Resectable Colon Cancer: Alliance (Cancer and Leukemia Group B) 9581 and 89803.

PURPOSE: Tumor levels of thymidylate synthase (TS), a target of 5-fluorouracil (5-FU)-based chemotherapy for colorectal cancer, have been studied as a predictive or prognostic biomarker with mixed results. PATIENTS AND METHODS: Tumor TS levels were prospectively evaluated in two adjuvant therapy trials for patients with resected stage II or III colon cancer. TS expression was determined by standard immunohistochemistry and by automated quantitative analysis. Tumor mismatch repair deficiency (MMR-D) and BRAF c.1799T > A (p.V600E) mutation status were also examined. Relationships between tumor TS, MMR-D, and BRAF mutation status, overall survival (OS), and disease-free survival (DFS) were investigated in the subset of stage III patients. RESULTS: Patients whose tumors demonstrated high TS expression experienced better treatment outcomes, with DFS hazard ratio (HR) = 0.67, 95% confidence interval (CI) = 0.53, 0.84; and OS HR = 0.68, 95% CI = 0.53, 0.88, for high versus low TS expression, respectively. No significant interaction between TS expression and stage was observed (DFS: interaction HR = 0.94; OS: interaction HR = 0.94). Tumors with high TS expression were more likely to demonstrate MMR-D (22.2% vs. 12.8%; p = .0003). Patients whose tumors demonstrated both high TS and MMR-D had a 7-year DFS of 77%, compared with 58% for those whose tumors had low TS and were non-MMR-D (log-rank p = .0006). Tumor TS expression did not predict benefit of a particular therapeutic regimen. CONCLUSION: This large prospective analysis showed that high tumor TS levels were associated with improved DFS and OS following adjuvant therapy for colon cancer, although tumor TS expression did not predict benefit of 5-FU-based chemotherapy. The Oncologist 2017;22:107-114Implications for Practice: This study finds that measurement of tumor levels of thymidylate synthase is not helpful in assigning specific adjuvant treatment for colorectal cancer. It also highlights the importance of using prospective analyses within treatment clinical trials as the optimal method of determining biomarker utility.

Importance of universal mismatch repair protein immunohistochemistry in patients with sebaceous neoplasia as an initial screening tool for Muir-Torre syndrome.

Muir-Torre syndrome, a Lynch syndrome variant, is characterized by sebaceous neoplasia plus one or more malignancies, typically colon cancer. The significance of DNA mismatch repair (MMR) deficiency detection by immunohistochemistry (IHC) in colorectal carcinomas is well established and is recommended as a screening tool for Lynch syndrome in newly diagnosed colorectal carcinomas. In comparison, literature on IHC application to detect MMR proteins (MLH1, MSH2, MSH6, and PMS2) in sebaceous neoplasia has been less studied and has been derived almost exclusively from tertiary care centers. Herein we describe the largest series to date characterizing MMR deficiency in sebaceous neoplasms, as well as the relative frequencies of each deficiency. Two hundred sixteen consecutive sebaceous neoplasms (216 patients) were analyzed from a community practice setting (133 sebaceous adenomas, 68 sebaceomas, 15 sebaceous carcinomas). One hundred forty-three were MMR deficient (66%), of which 90 were MSH2/MSH6 deficient (63%), 27 MLH1/PMS2 deficient (19%), 22 MSH6 deficient (15%), and 4 PMS2 deficient (3%). MMR deficiency was significantly associated with site, with tumors off of the head and neck more likely to be MMR deficient (specificity 96%). In contrast to prior reports, no significant trend in MMR-deficient versus -nondeficient tumors was seen in age at presentation (median age, 68 versus 66), tumor-infiltrating lymphocytes, or tumor type. Given the low sensitivity of age < 60 years (30%), location off of the head and neck (41%), or presence of tumor-infiltrating lymphocytes (29%) in MMR deficiency detection, IHC screening programs should test all sebaceous neoplasms for MMR deficiency, regardless of their clinicopathological features.

Targeted therapies and predictive markers in epithelial malignancies of the gastrointestinal tract.

CONTEXT: In recent years, there has been a tremendous amount of interest in the development of targeted therapies for the treatment of human cancers. Increased understanding of the specific molecular pathways and driver mutations critical to cancer cell growth have allowed the development of these advanced therapeutics. Among these, inhibitors of the epidermal growth factor receptor and HER2/neu pathways now play a major role in the management of gastrointestinal cancers in addition to other solid malignancies. In colorectal and gastric cancers, the use of epidermal growth factor receptor inhibitors and HER2/neu inhibitors has increased the available treatment options for patients with advanced disease. OBJECTIVE: To focus on the current targeted therapies and predictors of response in malignancies of the gastrointestinal tract. DATA SOURCES: Medical literature searchable on PubMed (US National Library of Medicine) as well as older studies revealed by the literature review were used as the source of data. CONCLUSION: Gene testing of critical elements of the pathways targeted by these agents (such as KRAS mutational analysis in colorectal tumors and HER2/neu testing in gastric cancers) allows the ability to predict which patients will respond to these treatments. As the molecular profiling of tumors and our understanding of cancer genomics and epigenetic alterations continues to grow, it is expected that these personalized targeted therapies will form one of the mainstays of gastrointestinal cancer treatment.

Immunohistochemical and molecular analysis of tyrosine kinase activity in desmoid tumors.

BACKGROUND: Optimal surgical and medical therapy for the treatment of desmoid tumors (DT) is still undefined. Partial response to tyrosine kinase inhibitors (TKI) has previously been described. Here, we examined the role of the tyrosine kinases c-Src and c-Kit in driving desmoid tumorigenesis. METHODS: Six consecutive DT and matched normal tissues were collected from the operating room. Tissues were embedded in paraffin for immunohistochemical analysis, and protein lysates were prepared for immunoblot and immunoprecipitation. RESULTS: We found increased levels of ß-catenin in five of six (83%) DT relative to matched normal tissue by immunoblot analysis. By immunohistochemistry, ß-catenin expression was also increased in DT and localized to the nucleus. In contrast, we observed variable levels of total and activated c-Src and c-Kit expression in DT compared with normal tissue. Finally, ß-catenin tyrosine phosphorylation (p-Y) among tumors was variably increased, despite the increased amount of total ß-catenin in tumors. CONCLUSIONS: Our results suggest that c-Src and c-Kit activity in DT is variable, consistent with the heterogeneous nature of this disease. Clinical response to TKI in DT may be via alternative mechanisms unrelated to c-Src or c-Kit activity. Further insight into DT biology will help identify novel drug regimens to limit the morbidity and mortality associated with this disease.

Microsatellite instability and loss of heterozygosity at chromosomal location 18q: prospective evaluation of biomarkers for stages II and III colon cancer--a study of CALGB 9581 and 89803.

PURPOSE: Colorectal cancer (CRC) develops as a result of a series of accumulated genomic changes that produce oncogene activation and tumor suppressor gene loss. These characteristics may classify CRC into subsets of distinct clinical behaviors. PATIENTS AND METHODS: We studied two of these genomic defects-mismatch repair deficiency (MMR-D) and loss of heterozygosity at chromosomal location 18q (18qLOH)-in patients enrolled onto two phase III cooperative group trials for treatment of potentially curable colon cancer. These trials included prospective secondary analyses to determine the relationship between these markers and treatment outcome. A total of 1,852 patients were tested for MMR status and 955 (excluding patients with MMR-D tumors) for 18qLOH. RESULTS: Compared with stage III, more stage II tumors were MMR-D (21.3% v 14.4%; P < .001) and were intact at 18q (24.2% v 15.1%; P = .001). For the combined cohort, patients with MMR-D tumors had better 5-year disease-free survival (DFS; 0.76 v 0.67; P < .001) and overall survival (OS; 0.81 v 0.78; P = .029) than those with MMR intact (MMR-I) tumors. Among patients with MMR-I tumors, the status of 18q did not affect outcome, with 5-year values for patients with 18q intact versus 18qLOH tumors of 0.74 versus 0.65 (P = .18) for DFS and 0.81 versus 0.77 (P = .18) for OS. CONCLUSION: We conclude that MMR-D tumor status, but not the presence of 18qLOH, has prognostic value for stages II and III colon cancer.

Five-year efficacy and safety analysis of the Adenoma Prevention with Celecoxib Trial.

The Adenoma Prevention with Celecoxib Trial examined the efficacy and safety of the cyclooxygenase (Cox)-2 inhibitor, celecoxib, for sporadic colorectal adenoma prevention in patients at high risk for colorectal cancer. The trial randomized 2,035 subjects to receive either placebo, celecoxib 200 mg twice daily, or celecoxib 400 mg twice daily. The primary study safety and efficacy analyses involved 3 years of treatment. The results showed significant antitumor effect but also indicated increased cardiovascular adverse events in patients treated with celecoxib compared with placebo. A total of 933 patients participated in an extension of the Adenoma Prevention with Celecoxib Trial, with a planned total treatment and surveillance duration of 5 years. Study medication was stopped early, resulting in a median treatment duration of 3.1 years for those with a year 5 colonoscopy. Patients treated on the placebo arm had a cumulative adenoma incidence of 68.4% over 5 years of observation. This figure was 59.0% (P < 0.0001) for those receiving low-dose celecoxib, and 60.1% (P < 0.0001) for those receiving high-dose celecoxib. The cumulative incidence of advanced adenomas over 5 years was 21.3% of those taking placebo, 12.5% (P < 0.0001) of those taking low dose celecoxib and 15.8% (P < 0.0001) of those taking high-dose celecoxib. Investigator reported treatment emergent adverse events were similar across all treatment groups for categories including renal and hypertensive events and gastrointestinal ulceration and hemorrhage events. For a category composed of cardiovascular and thrombotic events, the risk relative to placebo was 1.6 (95% confidence interval, 1.0, 2.5) for those using 200 mg twice daily celecoxib and 1.9 (95% confidence interval, 1.2, 3.1) for those using 400 mg twice daily celecoxib. Secondary analysis showed an interaction between a baseline history of atherosclerotic heart disease and study drug use with respect to cardiovascular and thrombotic adverse events (P = 0.004). These results confirm the inhibitory effect of celecoxib on colorectal adenoma formation, and provide additional safety data indicating an elevated risk for cardiovascular and thrombotic adverse events, particularly for patients with preexisting atherosclerotic heart disease.

Microsatellite instability predicts improved response to adjuvant therapy with irinotecan, fluorouracil, and leucovorin in stage III colon cancer: Cancer and Leukemia Group B Protocol 89803.

PURPOSE: Colon cancers exhibiting DNA mismatch repair (MMR) defects demonstrate distinct clinical and pathologic features, including better prognosis and reduced response to fluorouracil (FU) -based chemotherapy. This prospective study investigated adjuvant chemotherapy containing FU and irinotecan in patients with MMR deficient (MMR-D) colon cancers. PATIENTS AND METHODS: Cancer and Leukemia Group B 89803 randomly assigned 1,264 patients with stage III colon cancer to postoperative weekly bolus FU/leucovorin (LV) or weekly bolus irinotecan, FU, and LV (IFL). The primary end point was overall survival; disease-free survival (DFS) was a secondary end point. Tumor expression of the MMR proteins, MLH1 and MSH2, was determined by immunohistochemistry (IHC). DNA microsatellite instability was also assessed using a panel of mono- and dinucleotide markers. Tumors with MMR defects were those demonstrating loss of MMR protein expression (MMR-D) and/or microsatellite instability high (MSI-H) genotype. RESULTS: Of 723 tumor cases examined by genotyping and IHC, 96 (13.3%) were MMR-D/MSI-H. Genotyping results were consistent with IHC in 702 cases (97.1%). IFL-treated patients with MMR-D/MSI-H tumors showed improved 5-year DFS as compared with those with mismatch repair intact tumors (0.76; 95% CI, 0.64 to 0.88 v 0.59; 95% CI, 0.53 to 0.64; P = .03). This relationship was not observed among patients treated with FU/LV. A trend toward longer DFS was observed in IFL-treated patients with MMR-D/MSI-H tumors as compared with those receiving FU/LV (0.57; 95% CI, 0.42 to 0.71 v 0.76; 95% CI, 0.64 to 0.88; P = .07; hazard ratio interaction between tumor status and treatment, 0.51; likelihood ratio P = .117). CONCLUSION: Loss of tumor MMR function may predict improved outcome in patients treated with the IFL regimen as compared with those receiving FU/LV.

p27Kip1 in stage III colon cancer: implications for outcome following adjuvant chemotherapy in cancer and leukemia group B protocol 89803.

BACKGROUND: In retrospective studies, loss of p27(Kip1) (p27), a cyclin-dependent kinase inhibitor, has been associated with poor prognosis following colorectal cancer treatment. In a prospective study, we validated this relationship in patients enrolled on a trial of adjuvant chemotherapy for stage III colon cancer. METHODS: Cancer and Leukemia Group B protocol 89803 randomized 1,264 stage III colon cancer patients to receive weekly bolus 5-fluorouracil/leucovorin or weekly bolus irinotecan, 5-fluorouracil, and leucovorin (IFL). The primary endpoint was overall survival (OS); disease-free survival was a secondary endpoint. Expression of p27 and DNA mismatch repair proteins were determined by immunohistochemistry in primary tumor and normal tissue from paraffin blocks. Data were analyzed using log-rank test. RESULTS: Of 601 tumors analyzed, 207 (34.4%) showed p27 loss, 377 (62.8%) retained p27, and 17 (2.8%) were indeterminate. Patients with p27-negative tumors showed reduced OS [5-year OS 66%: 95% confidence interval (95% CI), 0.59-0.72 versus 75%: 95% CI, 0.70-0.79; log-rank P = 0.021]. This relationship was not influenced by treatment arm. Combination of p27 status with mismatch repair status, however, identified a small subset of patients that may benefit from IFL (n = 36; 5-year disease-free survival 81%: 95% CI, 0.64-0.98 versus 47%: 95% CI, 0.21-0.72; log-rank P = 0.042; 5-year OS 81%: 95% CI, 0.64-0.98 versus 60%: 95% CI, 0.35-0.85; log-rank P = 0.128). CONCLUSIONS: Loss of p27 is associated with reduced survival in stage III colon cancer but by itself does not indicate a significant difference in outcome between patients treated IFL or 5-fluorouracil/leucovorin.

O6-methylguanine DNA methyltransferase deficiency and response to temozolomide-based therapy in patients with neuroendocrine tumors.

PURPOSE: Recent studies suggest that temozolomide has activity in neuroendocrine tumors. Low levels of the DNA repair enzyme, O(6)-methylguanine DNA methyltransferase (MGMT), are associated with sensitivity to temozolomide in other tumor types. We evaluated the prevalence of MGMT deficiency in neuroendocrine tumors and correlated MGMT deficiency with treatment response to temozolomide-based regimens. EXPERIMENTAL DESIGN: The prevalence of MGMT deficiency, measured by immunohistochemistry, was assessed in 97 archival neuroendocrine tumor specimens. Rates of treatment response and survival were next evaluated in a cohort of 101 consecutive neuroendocrine tumor patients who had received treatment with a temozolomide-based regimen at one of three institutions. MGMT expression was directly correlated with treatment response in 21 patients who had available tumor tissue and response data. RESULTS: In archival specimens, MGMT deficiency was observed in 19 of 37 (51%) pancreatic neuroendocrine tumors and 0 of 60 (0%) carcinoid tumors (P < 0.0001). In the clinical cohort, 18 of 53 (34%) patients with pancreatic neuroendocrine tumors but only 1 of 44 (2%) patients with carcinoid tumors (P < 0.001) experienced a partial or complete response to temozolomide-based therapy. Among 21 patients with evaluable tumor tissue who had also received treatment with temozolomide, 4 of 5 patients with MGMT-deficient tumors (all pancreatic neuroendocrine tumors) and 0 of 16 patients with tumors showing intact MGMT expression responded to treatment (P = 0.001). CONCLUSIONS: MGMT deficiency, measured by immunohistochemistry, is more common in pancreatic neuroendocrine tumors than in carcinoid tumors as is treatment response to temozolomide-based therapy. Absence of MGMT may explain the sensitivity of some pancreatic neuroendocrine tumors to treatment.

Intraductal papillary mucinous neoplasm of the pancreas with loss of mismatch repair in a patient with Lynch syndrome.

Intraductal papillary mucinous neoplasm (IPMN) of the pancreas is a precancerous lesion with a well-described progression to carcinoma. This case report describes a 61-year-old woman with a history significant for multiple cancers and a confirmed germline mutation of MSH2, a mismatch repair gene responsible for Lynch syndrome, who was also found to have an IPMN of the pancreas. Phenotypic manifestations of Lynch syndrome in this patient included multiple adenomas and adenocarcinomas of the colon and also several other Lynch syndrome-associated cancers. The patient's adenocarcinoma of the colon and IPMN of the pancreas showed identical immunohistochemical staining profiles with loss of expression of MSH2 and MSH6 proteins and high levels of microsatellite instability. The immunohistochemical staining and microsatellite instability patterns of the adenocarcinoma of the colon and IPMN gives strong evidence to support the consideration of IPMN as part of the spectrum of lesions found in Lynch syndrome.